High speed percussion type drill stem



p 17, 1956 R. G. CLUGAGE 2,742,263

HIGH SPEED PERCUSSION TYPE DRILL STEM Filed June 18, 1948 2 Sheets-Sheetl livwmwywwxm M IIH MWi/WWA Pale/v (/0 aye April 17; 1956 Filed June 18,1948 R. G. CLUGAGE 2,742,263

HIGH SPEED PERCUSSION TYPE DRILL STEM 2 Sheets-Sheet 2 al mm UnitedStates Patent This invention relates to a high speed percussion typedrill. More particularly,-it relates to a drill comprising areciprocated rapidly in a bore or Well to perform the drilling operationby impact or percussion.

a In drills of the type referred to, a bit is provided and to the bit issecureda drill stem. The assembly is reciprocated by a cable which isoperated from the top of the well. The tool is rapidly reciprocated, andby impact of the bitagainst the earth or stone formation which is beingdrilled the drilling is accomplished. The bottom of the'well'issuppl'iedwith water, and from time to time the drilling operation isdiscontinued, the drill assembly is withdrawn and the mixture of waterand cut 7 tings is baled out.

'Drills of this type are used to drill relatively shallow wells, such aswater wells. The advantage of this type of drill over rotary drills isthe considerably less expensive construction of the drill and of. theequipment required at the surface of the well to'op'erate the drill.However, the effectiveness of this type'of drill is greatly limited. by

reason of the fact that it cannot be operated efficiently at high speed.Thus, if it is attempted to operate such a drill at a speed in excess ofabout 50 strokes per minute, the impact of the drill upon the formationis very inefficient.

It is an object of this invention to provide an improved type ofpercussion drill.

a It is a further object of the invention to provide a'high speedpercussion type of drill which operates efficiently at speeds of theorder of 100 strokes per minute. It is a still further object of theinvention to provide a high speed percussion drill of simple design suchas can be fabricated with a minimum of modification of a standardpercussion drill.

These and other objectsiof theinvention willbe ap 'parent from theensuing description and theappended of which is connected by means of aswivel joint to a cable 6. The bit 1 and the lower end of the drill stem3 are provided with polygonal neck portions and 11,

' drill bit, a drill stem, and a cable, and wherein the drill is Vrespectively, to engage a wrench, and an upper collar v 2,742,263Patented; Apr. 17., 19 5.6

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upon the collar 12. A hollow weight 14 having a central longitudinalbore 15 also encircles the drill. stem 4, the

bore 15 being of sufficient diameter that the drill stern willreciprocate freely therein.

Referring now to Fig. 2, the drill bit 1 and the cable 6 are the same asin Fig. 1, but a hollow stern 16is provided instead of a solid stem asin Fig. l, and. a coil spring 13 and a solid weight 17 are disposedwithin the hollow stem 16, as shown, with the spring resting. on thebottom of the stern and the weight resting on the spring.

16 is such as to allow the weight 17 to reciprocate freely therein. p

In operation, the drills shown in Figs. 1 and 2 are reciprocated in theusual manner but are capable of chicient operation at much greaterspeeds, .e. g;, to

strokes per minute; At such speeds, and with the usual drill, the impactforce of the bit on the downstroke would be negligible or zero owing tothe fact. that upward acceleration exerteduduring the upstroke exceedsthe acceleration of gravity on the downstroke. In. the drills of Figs. 1and 2, however, at speeds of the magnitude mentioned, the weight 14 or17 remains substantially stationary, thus causing compression of thespring 13 on. the upstroke. On the downstroke the expansive force of thespring adds to the force of gravity, thus allowing va much more rapidreciprocation of the bit. p p q The weight 14'or 17 is preferablyseveral times, :e. g. three times the weight of the bit. Where a deepwell is being drilled, say at 1000 feet, thusaddi-ng substantially tothe weight of the cable, a heavier weight and a stronger spring shouldbe used. Preferably, also, the drill is brought quickly to a high speed,and the length of stroke is preferably about two feet and the, speedisabout 150 strokes perminute in a well of ordinary depth, say downReferring now to Fig. 3, a solid stem 4 and a hollow weight 14a areemployed, as in Fig. l. However the hollow weight 14a'is provided withan enlarged bore or cavity 20 at its upper end providing ashouldef 21andthe solid stern 4 is provided with a flange'o'r collar 22 securedthereto about midway of the cavity 20." Disposed below the collar 22 isa coil spring 23 encircling the stem 4 and resting upon the shoulder 21,and disposed above the collar 22 is a second coil spring 24 encirclingthe stem 4 and resting upon the collar 22. As also shown thehollowweight 14a is provided with a cap 25 threaded onto the weight andremovable therefrom for purpose of assembly and repair. Also, the wallsj of the cavity 20 are slotted as at 26. Conveniently, four suchlongitudinal slots may be provided, spaced at intervals of 90 about theperiphery of the weight. As also shown, a swivel joint 5a is provided atthe bottom of the stem 4.

Referring to Fig. 4, a hollow drill stem 16, a solid weight 17 disposedwithin the hollow drill stem and a.

coil spring 13 disposed below the solid weight are provided as in Fig.2. However, a second coil spring 27 is also provided, being disposedabove the weight 17 and resting thereon. Referring to Fig. 5, a solidstem 4 and a hollow weight 30 are employed, the weight 30 being formedof two segments 30a and 30b in'threaded engagement at 31 to provideaccess for assembly and repair. A cavity a is formed in the weight 30,partly in the lower segment b and partly in therupper segment 30a, asshown. The solid stem 4 is provided with-a flange or collar 22 as inFig. 1, and a coil spring 23 encircles the stem below the collar 22 andrests upon the shoulder 21, while a second spring 24 is disposed abovethe collar 22 and also encircles the stem. As in Fig. 3, longitudinalslots 26 are provided in the walls of the cavity 20a.

The embodiments illustrated in Figs. 3, 4 and 5 have in common thefeature of a pair of coil springs. The coil springs 24 in Figs. 3 and 5and the coil'spring 13 in Fig. 4 are compressed on the upstroke, as inthe case of 'the coil springs 13 in Figs; 1 and 2, and serve toaccelerate the bit on the downstroke. These springs (13 and 24) may,therefore, be called the operative springs. The springs 23 in Figs. 3and 5 and the spring 27 in Fig. 4 are what may be called limit springs,which serve to limit the downstroke of the bit to prevent too hard ablow being struck.

In operation, the drills of Figs. 3, 4 and 5 are employed as describedabove with reference to Figs. 1 and 2, and similar considerations as torelative masses of the weight and bit are applicable. The longitudinalslots 26 in the drills of Figs. 3 and 5 are provided to allow egress ofwater which enters the cavity 20 or 20a. In the absence of such openingsthe collars 22 would act as pistons, thus retarding reciprocation of thedrills.

It will thus be seen that a high speed percussion drill has beenprovided which is effective in drilling at speeds two and three timesthe maximum efficient speed of ordinary percussion drills; that thedesign is simple and the parts easily fabricated; and that modificationof an ordinary percussion drill to embody the features described, may beaccomplished at very low cost.

While I have shown the preferred form of my invention, it is to beunderstood that various changes may be made in its construction by thoseskilled in the art without departing from the spirit of the invention asdefined in the appended claims,

I claim: a

1. A percussion drill comprising a drill bit, a drill stem attacheddirectly to said drill bit, said drill stem being provided with aprojecting member, a coil spring encircling said drill stem andsupported upon said projecting member, and a hollow weight receivingsaid drill stern, freely movable therealong and resting upon saidspring, said weight being of sufficiently greater mass than said bit andstem to maintain the weight substanftially stationary when said bit andstem are reciprocated rapidly.

2. A percussion drill comprising a drill bit,. a drill stem attacheddirectly to said drill bit, a hollow weight receiving said drill stemand freely movable therealong and supported thereby, said weight havingan enlarged cavity formed therein, and a coil spring disposed withinsaid cavity, encircling and supported by said drill stem at a pointsubstantially below the upper end of said cavity against downwardmovement and so disposed with relation to said weight as to becompressed on the upstroke of the drill stem and to expand against saiddrill stem on the downstroke, said weight being of sufliciently greatermass than said bit and stem to maintain the weight substantiallystationary when said bit and stem are reciprocated rapidly.

3. The drill of claim 2, wherein said drill stem is provided with aprojecting member disposed medially of said cavity and said coil springis disposed thereabove and is supported thereby, said drill alsoincluding a second coil spring encircling said drill stem and disposedwithin said cavity with its ends abutting the bottom of said cavity andsaid projecting member.

4. A percussion drill comprising a drill bit, a hollow stem directlyconnected to said drill bit, a coil spring supported within said stemand at the lower end thereof and extending longitudinally thereof, and aweight disposed within said stem, resting upon said spring and freelymovable longitudinally of said stem, said weight being of sutficientlygreater mass than said bit and stem to maintain the weight substantiallystationary when said bit and stem are reciprocated rapidly, and a secondcoil spring disposed within said hollow stem above said weight andresting thereon, the upper end of said spring abutting the upper end ofsaid stem.

5. A percussion drill comprising: a drill stem; a drill bit secured tothe lower end of said stem; an elongated annular weight circumscribingand freely slidable over said drill stem, said weight being formed witha cage intermediate its ends; a coil spring disposed in said cage aboutsaid drill stem with its upper end in abutment with the upper end ofsaid cage; and a stop member fixed to said drill stem adjacent the lowerend of said spring and serving as a stop therefor.

References Cited in the file of this patent UNITED STATES PATENTS

